but instead invest into gameplay.
Example: Civilization I was a great game, not because it had such nice graphics or sound effects but because of the complexity of the game play. But the interface was easy to use, the different types of terrain and units easy to recognize and it was easy to pick up the strategy. Also, it worked on rather minimalistic hardware. (And, I have to admit, I originally got it as a pirated copy, but I bought it later. But since the bought version came with copy protection I continued to use the pirated one.) Now look at the latest installments of that series. The graphics and sound are improved but that also results in units and terrain being much harder to recognize. The gameplay is basically unchanged. But it requires so much computing power that the later stages of the game become basically unplayable if you don't run it on a top of the notch machine.
I have switched back to playing Civilization I when I am in the mood.

I just realised that this does not really answer the original question (I should have read it, not just the title)....

"Der Steppenwolf" from Hermann Hesse was required literature at school and despite that I read it and it possibly saved my life.
At that time I was thinking seriously about suicide and when I read the following quote from the main character, something along the lines "you can always commit suicide later if it gets too hard, so just keep going for now"
(I don't remember the exact words and it is in German anyway, so it wouldn't be of any use here)
That absolutely made sense to me. As long as you are alive, things can improve, once you are dead, you are dead and that's it.

There have been other important books later but I think the above is quite fundamental so no other became as significant as that one book.

The Star, by Arthur C. Clarke (http://en.wikipedia.org/wiki/The_Star_(short_story) ) At least, if you believe in Christian mythology you will find it rather depressing that god chose to let the star of such a great civilization go nova just to generate the star of Bthlehem.

Yes, I know, "phablet" is a stupid name, but the Samsung Galaxy Note (the smartphone, not the tablet) with the Kindle software makes an excellent e-book reader. You have to get used to the size, though. It is huge for a phone and maybe a little bit too small for a tablet, but in my view exactly right for an e-book.

I own a Samsung Galaxy Note and I knew beforehand how large it is. But I didn't buy a mobile phone, I bought a small tablet with mobile Internet connection and that's exactly what I got. Yes, I can also make phone calls with it, but I rarely do. As for carrying it: There are nice belt pouches for it. The solution is simple: If you don't like it, don't buy it. Of course, if somebody can come up with a smartphone that has a >=5" display but is much smaller, that would be nice. Maybe with glasses? That would still leave the problem on how to interact with it (no, speech recognition is not a solution). We'll see.

... so will there be "Glass" in the strength I need for my eyes? (I am still looking for sun glasses that are worth that name, preferably mirror sunglasses, in the strength I need. All they try to sell me are slightly darkened glasses and these are not even worth considering.)

... is far from perfect. Depending on which measure us use, Germany ranks somewhere in the top middle of the statistics. And it is definitely bad for both extremes of students: Those that are really bright and those that are - em - "intellectually challenged".

Why does that matter? You can still answer "What's your mother's maiden name?" with stuff from a book.